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Satellite altimetric time series allow high-precision monitoring of ice-sheet mass balance. Understanding elevation changes in these regions is important because outlet glaciers along ice-sheet margins are critical in controlling flow of inland ice. Here we discuss a new airborne altimetry dataset collected as part of the ICECAP (International Collaborative Exploration of the Cryosphere by Airborne Profiling) project over East Antarctica. Using the ALAMO (Airborne Laser Altimeter with Mapping Optics) system of a scanning photon-counting lidar combined with a laser altimeter, we extend the 2003–09 surface elevation record of NASA’s ICESat satellite, by determining cross-track slope and thus independently correcting for ICESat’s cross-track pointing errors. In areas of high slope, cross-track errors result in measured elevation change that combines surface slope and the actual Δz/Δt signal. Slope corrections are particularly important in coastal ice streams, which often exhibit both rapidly changing elevations and high surface slopes. As a test case (assuming that surface slopes do not change significantly) we observe a lack of ice dynamic change at Cook Ice Shelf, while significant thinning occurred at Totten and Denman Glaciers during 2003–09.

The amino acid sequence of the small copper protein
auracyanin A isolated from the thermophilic photosynthetic
green bacterium Chloroflexus aurantiacus has been
determined to be a polypeptide of 139 residues. His58,
Cys123, His128, and Met132 are spaced in a way to be expected
if they are the evolutionary conserved metal ligands as
in the known small copper proteins plastocyanin and azurin.
Secondary structure prediction also indicates that auracyanin
has a general β-barrel structure similar to that of
azurin from Pseudomonas aeruginosa and plastocyanin
from poplar leaves. However, auracyanin appears to have
sequence characteristics of both small copper protein sequence
classes. The overall similarity with a consensus sequence
of azurin is roughly the same as that with a consensus
sequence of plastocyanin, namely 30.5%. We suggest that
auracyanin A, together with the B forms, is the first example
of a new class of small copper proteins that may be descendants
of an ancestral sequence to both the azurin proteins occurring
in prokaryotic nonphotosynthetic bacteria and the plastocyanin
proteins occurring in both prokaryotic cyanobacteria and
eukaryotic algae and plants. The N-terminal sequence region
1–18 of auracyanin is remarkably rich in glycine
and hydroxy amino acids, and required mass spectrometric
analysis to be determined. The nature of the blocking group
X is not yet known, although its mass has been determined
to be 220 Da. The auracyanins are the first small blue
copper proteins found and studied in anoxygenic photosynthetic
bacteria and are likely to mediate electron transfer between
the cytochrome bc1 complex and the
photosynthetic reaction center.

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